1. Field of the Invention
The present invention relates to a reading apparatus for performing colorimetry of a color pattern formed on a sheet, and a printing apparatus including the reading apparatus.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2008-281549 discuses an ink jet printer including a colorimetric apparatus. This colorimetric apparatus performs colorimetry of a printed color pattern for color calibration and, based on colorimetric data, adjusts colors of a color image to be subsequently printed, thus reproducing desired colors. The printer records color patches as a color pattern for color calibration, and then the colorimetric apparatus performs colorimetry of the color patches with a colorimetric sensor moving in the sheet width direction.
With the colorimetric apparatus discussed in Japanese Patent Application Laid-Open No. 2008-281549, with the sheet being pressed by a presser plate, a wheeled carriage on which a colorimetric sensor is mounted runs on the presser plate, and the colorimetric sensor reads color patches, thus performing colorimetry. When the carriage on which the calorimetric sensor is mounted separates from the presser plate, the presser plate rotatably shifts to separate from the sheet.
When performing sheet colorimetry, the colorimetric apparatus discussed in Japanese Patent Application Laid-Open No. 2008-281549 rotatably shifts a presser plate, which is regularly raised, to press a sheet. Subsequently, a carriage on which the colorimetric sensor is mounted moves to the presser plate and then reads the color patches while moving thereabove.
With this configuration, while the carriage exists above the presser plate, it is not possible to rotate the presser plate to retract the carriage. Specifically, to release the pressing by the presser plate to move the sheet, it is necessary to retract the carriage to the outside of the presser plate. The carriage reads the color patches only in the forward path and returns to a home position in the backward path (back feed). Before the carriage completes back feed (backward path) and retracts from above the presser plate to the outside, a following sheet cannot start being moved. This means that the time loss required for back feed disturbs the improvement in reading throughput. In particular, this issue will become distinct when sequentially reading a number of test patterns through repetitive carriage operations.
With the colorimetric apparatus discussed in Japanese Patent Application Laid-Open No. 2008-281549, when the wheel of the carriage runs upon the presser plate, the wheel passes the level difference for the thickness of the presser plate and the impact is transmitted to the carriage. Repetitively applying this impact to the carriage may cause degradation in the attachment accuracy of the colorimetric sensor or a failure of the colorimetric sensor. When the carriage is retracted to the outside of the presser plate, the wheel of the carriage travels on the sheet without the presser plate. Accordingly, when the sheet has a pattern or image printed thereon, the pattern or image may be damaged by the track of the wheel. Each of these factors may cause degradation in reading accuracy.